Regensburg 2007 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 23: Nanoelectronics II - Spintronics and Magnetotransport

TT 23.2: Talk

Thursday, March 29, 2007, 09:45–10:00, H19

Combining Ferroelectricity, Magnetism, and Superconductivity in Tunnel Junctions — •Hermann Kohlstedt¹, Nicholas Pertsev^1,2, Adrian Petraru¹, Ulrich Poppe¹, and Rainer Waser¹ — ¹Institut für Festkörperforschung and CNI, Forschungszentrum Jülich, Jülich, Germany — ²A. F. Ioffe Physico-Technical Institute, St. Petersburg, Russia

Complex oxides display a rich variety of physical phenomena including magnetism, superconductivity, and ferroelectricity. First, we will present our theoretical and experimental results on the so-called ferroelectric tunnel junctions (FTJs). These junctions consist, e.g., of SrRuO₃/BaTiO₃/SrRuO₃ trilayers grown on SrTiO₃ by high-pressure sputtering. The heterostructures were investigated by means of x-ray diffraction to determine crystallographic structure and lattice strains. Then the electrical properties of FTJs were determined by resistive transport measurements and by recording the polarization-voltage hysteresis loops. Size effects observed in ultra-thin ferroelectric films will be discussed, as well as the theoretical models of the interplay between electron tunneling and polarization state of the barrier. Second, we will provide an overview for the current status of the international studies of the so-called multiferroic tunnel junctions. By combing ferroelectric or multiferroic tunnel barriers with ferromagnetic and/or superconducting electrodes, a whole *zoo* of novel tunnel junctions can be proposed. The results already obtained for these new types of tunnel junctions and the theoretical and experimental challenges existing in this area will be discussed.